Recovery of elemental sulfur from acidic gases



Feb. 14, 1950 s. NEVINS ET AL 2,497,095

RECOVERY OF ELEMENTAL SULFUR FROM ACIDIC GASES Filed Jan. 25, 1945 eSheets-Sheet 1 run man no iano INV I Jamaal Z. 17mm By fdfi l & 6111mm,fit

HTTOR/VEY 5 Feb. 14, 1950 s. L. NEVINS ET AL 2,497,095

RECOVERY OF ELEMENTAL SULFUR mom ACIDIC GASES Filed Jan. 25, 1945 v 6Sheets-Sheet 2 INVENTOR Jamaal Z. Aim/ms BY fines .3? 6171mm, I]:

Feb. 14, 1950 r s. L. NEVINS ET AL RECOVERY OF ELEMENTAL SULFUR FROMACIDIC GASES Filed Jan. 25, 1945 6 Sheets-Sheet 4 v INVENToRs Jamaal Z.Nevins 'BY fi ms 5. 6111mm, J1:

N MN Feb. 14, 1950 s. L. NEVINS El AL RECOVER}! ox ELEMENTAL SULFUR momACIDIC GASES Filed Jan. 25, 1945 6 Sheets-Sheet 6 30 326066 :00 T cea ccat; ca

HF I" [EUR 11' QK Z' INVENTORS L M01) M49 6: (iii/mm, ft.

(2.34. MJM Qd- Patented Feb. 14, 1950 RECOVERY OF ELEMENTAL SULFUR- FROMACIDIC GASES Samuel L. Nevins, Little Rock, Art, and James S.

Gilliam, Jr., Shreveport, La.,

m n s. y

mesne assignments, to Mathieson Chemical Corporation, New York, N. Y acorporation of Virginia Application January 25, 1945, Serial No. 574,606

15 Claims.

This invention relates to the recovery of elenental sulphur from acidicgases containing sulphur compounds, and is more particularly directed tothe treatment of hydrogen sulphide and hydrogen sulphide containinggases commonly thrown off as waste product in the refining or treatmentof petroleum, natural gas, manufactured gas and chemicals.

The waste gases separated in the various purification processes employedin the manufacture of commercial natural gas, coke oven gas, andpetroleum products, normally contain sulphur in the form of hydrogensulphide and. in addition thereto, usually contain water vapor andvarious gaseous materials in the form of carbon dioxide, carbonmonoxide, hydrogen, and in many instances sundry hydrocarbons such asmethane, ethane, and propane. Again, in some waste gases are found suchsulphur compounds as hydrogen sulphide, sulphur dioxide,carbonoxy-sulphide, carbon disulphide, and in certain circumstances,alkyl sulphides together with gaseous parailinic and olefinichydrocarbons, carbon dioxide, watervapor and hydrogen, v

Certain chemical treating plants may produce waste acidic gasescontaining recoverable amounts of sulphur compounds, usually mixed orcombined with impurities. For example, plants for the manufacture ofcarbon disulphide from sulphur and methane throw oif waste acidic gascontaining sulphur vapor, hydrogen sulphide, methane and otherhydrocarbons.

Attempts have been previously made to recover commercially profitableyields of elemental sulphur from such waste acidic gases but withoutsuccess, since the reactions which are reputed to occur in the treatmentof hydrogen sulphide gases are not realized when working with relativelyimpure gases, which may be explained in part by reaction'disturbancescaused byother gaseous impurities and materials which the waste inputgas contains. It has therefore been common practice to burn such wasteacidic gas in flare towers or under boilers, since such waste acidicgases have an obnoxious odor and are lethal in, character and hencecannot be discharged into the atmosphere.

This invention is directed to a novel and comsuch waste acidic gases areprocessed in accordance with this invention, such waste acidic gasesconstitute a valuable source of material from which commerciallyprofitable yields of sulphur of highrpurity may be obtained in aneconomical manner by continuous operation, with the final efliuent gassubstantially devoid of sulphur compounds and in condition for dischargeto the atmosphere.

An object of this invention is to provide an improved process for thetreatment of waste acidic gases containing sulphur compounds wherebyelemental sulphur of high quality may be recovered therefrom in a highlyeconomical and practical manner.

Another object of this invention is to provide an improved process forthe treatment of waste acidic gases containing sulphur compounds wherebythe obnoxious and toxic constituents may be substantially completelyremoved therefrom, thereby providing a resulting eiiiuent gas, unharmfulto animal and plant life.

Another object of this invention is to provide a highly economical andefilcient process for the recovery of elemental sulphur from wasteacidic gases containing hydrogen sulphide cast off from refining, gastreating and chemical operations, whereby substantially all of thesulphur compounds in such gases are removed and recovered in the form ofuseable elemental sulphur.

A still further object of this invention is to provide a novel processfor the production of elemental sulphur from waste acidic gasescontain-- lng sulphur in a combined state, which process can be carriedout without the application of external heat, and whereby heat valuesare generated which can be advantageously converted into steam or otheruseful heat forms.

A further object of this invention is to provide a process for theeifective conversion of waste acidic gases containing hydrogen sulphideor relatively pure hydrogen sulphide by successive and merciallypractical method for treating such variant types of waste acidic gasescontaining sulphur compounds which are in suflicient concentration towarrant commercial recovery, and a characterizing feature oftheinvention is its wide permissible availability for treating numeroustypes of sulphur-containing gases. When continuous treatment of thewaste gases in a reaction zone and one or more catalytic conversionzones to produce elemental sulphur vapor, and thereafter condensing theproduced sulphur vapor to elemental sulphur of high purity, at low costand with a high recovery yield.

Other objects and advantages of this invention will be more readilyunderstood and comprehended from the following disclosure.

The essential features of the process and the permissive range ofoperating latitude will be apparent from a consideration of the severalillus- 3 trative physical embodiments of the invention shown in theaccompanying drawings.

For more ready comprehension of the invention and the chemical andphysiochemical factors involved in the process, there is shown in theaccompanying drawings a series of embodiments of physical structure inwhich:

Fig. 1 is a diagrammatic side elevational view of a complete plant inwhich this novel process may be carried out Fig. 2 is a diagrammatic topplan view of the plant shown in Fig. 1;

Fig. 3 is an enlarged view of the reaction furnace wherein the initialpart of the reactions takes place, this view being partly in elevationand partly in vertical cross-section to more clearly illustrate theconstruction and details of the furnace as the same appears when viewedalong line 3-4 of Fig. 4;

' Fig. 4 is another enlarged view of the reaction furnace shown partlyin horizontal cross-section and partly in elevation as the same appearswhen viewed along line 4-4 of Fig. 3;

Fig. 5 is an enlarged vertical cross-sectional view of the reactionfurnace as the same appears when viewed along line 5-5 of Fig. 3; and

Fig. 6 is a diagrammatic side elevational view of a highly effective butmore simplified form of plant for the recovery of elemental sulphur fromwaste acidic gases containing sulphur compounds.

Similar reference characters refer to similar parts throughout theseveral views of the drawings and specification."

In carrying out the process, the input waste acidic gas is analyzed todetermine the approximate quantities of gaseous materials containedtherein. As the first step in the process, a stoichiometric amount ofoxygen, as in the form of air, is added to the input waste acidic gasesto be treated. In determining this stoichiometric balance, considerationis given to the quantity of oxygen necessary to convert the hydrogensulphide content of the waste acidic gas to free sulphur, the quantityof oxygen which would be given up during the reaction by otheroxygencontaining gases and materials, and the oxygen required by othergaseous components and materials in the input waste acidic gas to effectoxidation thereof. By thus determining and controlling thestoichiometric amount of oxygen required in the various reactions whichproceed in the system, an actual sulphur recovery of 90 per cent or moreof the theoretical recovery can be obtained, even with waste acidicinput gases containing as low as 15 to 20 per cent hydrogen sulphidecontent.

In light of the above, it is apparent that the stoichiometric amounts ofair must be carefully adjusted. If more than the stoichiometric balanceof oxygen is present, an excess of sulphur dioxide will appear in-thetail gases from the system; on the other hand, if materially less thanthe stoichiometric amount of oxygen is fed to the system, an excess ofhydrogen-sulphide will be discharged in the tail gases. It is possibleby employing an excess of air to react all of the hydrogen sulphide inthe entering waste acidic gases, but in these circumstances an excessamount of sulphur dioxide is formed which is unavailable for theconversion of elemental sulphur unless additional hydrogen sulphide isfed 7 into the system to effect reaction.

It is important to observe that the presence of carbon dioxide in theentering waste acidic 10 to carbon dioxide and sulphur, and that thepresence of hydrocarbon compounds in the entering waste acidic gasesdoes require sufllcient additional air to establish substantialstoichiometric balance if maximum sulphur recovery is to be attained.

As will be appreciated, important factors in establishing andmaintaining the emciency of the process are careful quantitative controlof the air fed to the reaction zone and the complete and homogeneousmixing of the reactants to insure a substantially quantitative reaction.The theoretical formula for determining th proper air and entering wasteacidic gas proportion is two mol volumes of hydrogen-sulphide in theentering waste acidic gas to one mol volume of oxygen in air (one molvolume equals 379 cu. it. at 60 F. and 14.73 lbs. per sq. in. abs).Assum ing that a typical gas to be processed will contain approximately50 per cent hydrogen sulphide,

the theortical quantity of the sour gas charged per unit of time isdetermlned'as follows: 2H,S lg

5 5 X 2 1516 cu. ft. of acidic gas at 60 F. and 14.73 lbs. per sq. in.absolute The same quantitative amount of air (21% O2) required in thereaction per unit of time similarly is determined as follows:

8 on. t. of air at and 14.73lbs. per sq. in. absolute In order toachieve stoichiometric balance it is necessary to make a carefulanalysis of the entering waste acidic gases so that stoichiometricbalance can be computed. All of the reactive gases which contain sulphurfed into the unit must be considered in computing the stoichiometricbalance. Thus, in addition to hydrogen sulphide, such gaseous compoundsas sulphur dioxide, carbon disulphide and carbonoxy-sulphide if present,should be considered. Also, in

computing the stoichiometric balance, the hydrocarbons present in theentering waste acidic gases must be taken into consideration and asufllcient amount of oxygen supplied to react therewith to form carbondioxide and water change in the quantity of air to consume the excesshydrocarbons. A large quantity of hydrocarbons in the acid gas fed,should be avoided because a large volume of hydrocarbons may tend todeposit carbon in the system with con-- sequent danger of contaminatingthe recovered sulphur, and cause a higher stack loss of hydrogensulphide and sulphur dioxide. Thu process described herein is, however,designed for a relatively wide permissive latitude in hydrocarboncontent and can accommodate the hydrocarbons normally encountered inacid gas without producing appreciable carbon deposits or stack loss.

In a typical operation therefore, assuming the gas does not require theaddition of air beyond entering waste acidic gas contains 50 per cent ofturbulent flow and temperature as to insure complete and homogeneousmixing.

In the preferred or optimum operation of the process, it is desirable tosecure a substantially complete conversion of the waste acidic gases notonly to recover the greatest amount of valuable elemental sulphur, butalso to reduce the content of the hydrogen sulphide and sulphur dioxidein the effluent gases so that such emuent gases will not constitute anuisance when discharged into the atmosphere. In such preferredoperation, the eiiiuent reaction gases discharged from the primaryreaction zone are substantially reduced in temperature and moved intocontact with catalytic material to insure oxidation of any remaininghydrogen sulphide and the reduction of contained sulphur dioxide (S02),carbonoxy sulphide (COS) and carbon disulphide (CS2) to sulphur vapor.By such catalytic treatment of the reaction gases discharged from thereactor, approximately 85 to 90 per cent of the sulphur compounds in thewaste acidic gas may be converted into elemental sulphur vapor. The thustreated reaction gases are then preferably further reduced intemperature and scrubbed and cooled with a scrubbing and cooling agent,such as molten sulphur, to condense the sulphur vapors and recover thecondensed sulphur. As a further refinement, the scrubbed gases thusproduced may be given a further pass through an additional catalyst bedto reduce remaining amounts of unreacted gases to sulphur vapor, whichvapor is removed by scrubbing and cooling treatment. By pursuing thisfurther step, it has been found that 95 per cent of the availablesulphur in the waster acidic gas may be removed and recovered asvaluable elemental sulphur.

No external source of heat is employed after the process has been placedin operation. On the contrary, the heat of the reaction carried out asthe initial step in the reaction furnace results in a reaction gastemperature of from approximately l600 to 2400 F., which heat ofreaction may be advantageously extracted and utilized in the productionof steam.

The production of one long ton of sulphur according to the process willproduce approximately 6,000 pounds of steam at 300 pounds pressure whenacid gas containing approximately 50 percent hydrogen sulphide isprocessed.

It would appear that the oxidation of the hydrogen sulphide content ofthe gas to elemental sulphur should be a relatively simple operation,which presumably would proceed according to the equation- (1) zms--oi-asiq-zmo by mixing sulphur It has been ascertained, however, thatthe conversion is not such. a simple matter because the of the reactionstaking place, and the changes in the reactions occur under differenttemperature conditions. For example, when the waste acidic .of reactionstake place in the reaction furnace,

as indicated by the following equations:

It will be noted, from an inspection of Equations 2 and 3, that bothelemental sulphur and sulphur dioxide are formed in the reactionfurnace. These two reactions proceed simultaneously, but at a differentreaction rate, so that when the reactions are completed, the reactiongases will contain both gaseous sulphur and sulphur dioxide.

It is important to observe at this point that carbon dioxide content ofthe waste acidic gas (see Equations 4 and 5) reacts with hydrogensulphide to form carbonoxy-sulphide and carbon disulphide, thus reducingthe amount of elemental sulphur which is formed, at this stage ofrecovery. This situation is aggravated when the reaction gases arecooled, as, for example, in

a boiler in a manner to be described. Under the,

lowered temperature conditions obtaining in the boiler, the followingseries of reactions appear to take place:

boiler are further reduced in temperature in the preheater. Under thenew equilibrium conditions obtaining in the preheater, additionalreactions take place, as is indicated by the following equations:

(14) COS-l-H2O- CO2+H2S (15 2H=o+1 si s0=+2His Assuming that theentering waste acidic gases contain no carbon dioxide, hydrocarbons orother reaction impurities, and that the stoichiometric amount of air isfed to the furnace, the furnace eilluent reaction gases will containsulphur vapors, sulphur dioxide and hydrogen sulphide instoichiometrically balanced amounts in the approximate equilibrium atthat particular temperature. This equilibrium, however, is not the sameat different temperatures. When thefurnace eilluent reaction gases arecooled, as in the boiler, a new equilibrium is established at such lowertemperature with the formation of additional sulphur vapor due to thereaction between some of the hydrogen sulphide and sulphur dioxide.-

, If the waste acidic gases to be treated contain a substantial amountof carbon dioxide, the exit furnace gases, stoichiometrically balanced,may contain no hydrogen sulphide although it would be expected that suchfurnace eiliuent reaction gases would contain a small amount of hydrogensulphide. The substantial absence of the hydrogen sulphide may beexplained by the fact that the carbon dioxide content of the wasteacidic gas reacts with hydrogen sulphide (see Equations 4. and 6) toform substantial amounts of elemental sulphur vapor and sulphurcompounds which may subsequently be converted to elemental sulphur. Itwill thus be seen that the presence of substantial amounts of carbondioxide in the entering waste acidic gases serves to effectsubstantially complete elimination of the hydrogen sulphide at the exitof the reaction furnace. When such reaction gases are cooled. however,some of the sulphur vapor reacts with carbon dioxide, carbon monoxide.and water, according to Equations 10, l1 and 13.

When the furnace eflluent reaction gases, after The gas line I conductsthe waste acidic gas to some cooling, are contacted with a suitablecatalyst in the converter, further reactions occur according to thefollowing equations:

A difllculty with previously known processes for the recovery of sulphurfrom hydrogen sulphide is that other gases and impurities are commingledwith the input gas containing hydrogen sulphide which have resulted infailure to obtain proper recovery reactions or a commercially profitablerecovery of sulphur.

In accordance with this invention, the process is adapted for flexibleoperation so as to recover sulphur from sulphur-containing gases havingcommingled therewith various other non-sub phurous gases and materials,with resultant high sulphur recovery. The sulphur-containing gases fedinto the unit are first analyzed to determine the approximate quantitiesof various gaseous materials contained therein, and conversion iseffected by adding a stoichiometric amount of oxygen, asin the form ofair, to the input gases. It will here be appreciated that sufficientoxygen is added to convert the hydrogen sulphide gas to free sulphur,minus the oxygen which would be given up in reaction by theoxygen-containing gases, or plus the amount of oxygen which the othergases in the input stream would absorb in the oxidation thereof. By thusfirst determining the stoichiometric amount of oxygen required tooxidize the input gases of' a given analysis, an actual sulphur recoveryof 90 per cent or more of the theoretical recovery can be obtained, evenwith input gases containing as low as per cent hydrogen sulphidecontent.

By way of example, acidic gases have been treated containing as low as20 per cent hydrogen sulphide and up to 70 per cent hydrogen sulphide,the remainder being largely carbon di oxide with a small amount of waterin vapor form and a small quantity of hydrocarbon gases. Whenapproximate stoichiometric balance was obtained by the addition of air,conversion in each instance proceeded smoothly and without the intakeside of a reaction furnace, which, as shown in Figs. 3, 4 and 5, maycontain one or more reaction zones 3. To supply each reaction zone, thesupply line I leads into a manifold 4 having branch lines 5, 6 and I,which lead to the respective reaction zones 3. The feed line I, as shownin Fig. 1, has interposed therein the control valve 8 and the indicatingflow meter 8. The main gas feed line I may also be connected with abranch line It, having the interposed control valve H and flow meter [2,through which a portion of the entering waste acidic gas may be suppliedto the system at a secondary reaction zone for a purpose and in a mannermore particularly to be described.

The air required for the operation is admitted through line H and forcedby blower 15 through the line l5 and branches l1, l8 and I 9 to thereaction zones 3 positioned within the furnace 2. The line 16 isprovided with a block valve 20 and flow meter 2|. The blower I5 is ofsuflicient capacity to insure the required air for the reaction and toforce the gaseous products of reaction through the system.

The air supply fed to the reaction furnace 2 through the air supply lineI 6 is carefully controlled by providing the outlet of the blower ISwith a by-pass line H which leads into the air entry line l3. The volumeof air forced through air supply line I6 is controlled by a pyrometerrecorder controller 22 which is connected by a thermo-couple 22'established in the furnace interruption, with recovery of 90 per cent or.70

more of free sulphur.

There are shown in Figs. 1 and 2 diagrammatical views of a commercialplant which may be designed to any desired size to treat a relaexit gasduct 65. A motor valve 23, connected into air by-pass line I4, iscontrolled by the pyrometer recorder controller 22 in accordance withthe variations in temperature of the furnace exit gases, as indicated bythe thermo-couple 22'. A hand-operated valve 23' may also be installedin by-pass line H for manual regulation of air volume passing throughair supply line l5. It will be appreciated that a flow ratio controllercould also be used to control the volume of air through line It, inaccordance with the variations in volume of acidic gas flow to thesystem through supply line I. By thus properly controlling volume of theair and entering waste acidic gas fed, losses by way of hydrogensulphideand sulphur dioxide can be reduced to 1 per cent or below of theeflluent gases discharged from the plant, equivalent to an over-allsulphur conversion efficiency of from to 98 per cent during continuousoperation.

The furnace and reaction zones therein are designed so that concurrentstreams of entering waste acidic gas and air are contacted andhomogeneously mixed in passageways or conduits, which latter are heatedby the high temperature products of reaction. As will be seen, the flowof gases through the reaction zones is essential- 1y regenerative, thusestablishing a turbulence which positively insures homogeneous mixingand uniform distribution of heat through the gas mixture. I

.The furnace would normally be designed to withstand pressures of about5 lbs. per sq. in. It is found in actual practice that the internalfurnace pressures do not materially exceed 2 ,4

tively small amount to many millions of cubic 7 lbs. per sq. in. Suchfurnace pressures, as will flow.

be appreciated, are established and controlled by the back pressuredeveloped through the system. The back pressure may vary, particularlyif the system becomes fouled or particularly corroded resulting in anincreased resistance to Therefore the furnace should be designed with asufficient factor of safety to take possible back pressure into account.

The reaction furnace, as shown more particularly-in Figs; 3, 4 and 5,comprises an enclosed container having an externalshell 24 built up ofheavy steel plate. The furnace may be either generally circular orpolygonal in cross-section with enclosing end walls 25 which close theends of the body wall. The furnace shown in Figs. 3, 4 and isillustrated as having a body wall of generally circular cross-sectionand for couvenience in description, the body wall will be designated ascomprising a bottom wall section 25, a top wall section 21, a rear wall.section 23, and a front wall section 23 enclosed between the end wallsections 25. The interior walls of the furnaces are lined with suitablerefractory and heat insulating material which ma consist of a layer 30of suitable plastic insulating material, a layer 3i of light weightinsulating brick and an inner layer 32 of firebrick.

The furnace may be of any desired length and diameter depending upon theproduction capacity desired. By way of example, such a furnace may havean internal diameter of approximately 8 feet and an internal length ofapproximately 24 feet. The furnace is divided into reaction compartmentswhich define the reaction zones 3 by a plurality of dividing partitions33, as shown more particularly in Figs. 3 and 4, which present solidwalls built up from suitable firebrick. The dividing partitions or walls33 extend from the bottomwall section-26 of the furnace to the top wallsection 21 thereof and also to the rear wall section 23 of the furnace.It will be noted by referring to Fig. 4 that the front edge 34 of eachdividing wall 33 extends short of the front wall section 23 of thefurnace to define a passageway 35 therebetween which communicates withthe adjacent reaction zone 3. Thus it will be noted that the divisionwalls 33 extend across approximately four-fifths of the internalcross-sectional area of the furnace.

Leading into each chimney 44 is an entrance passageway 36 which isdefined by a collar 31 built up of steel plate which is welded orotherwise secured to the top wall section 21 of the furnace. The steelcollar 31 is suitably lined with refractory brick 38. The top of eachentrance passageway 35 is closed by a steel plate 39 whose inner surfaceis also lined with refractory material 40. Each of the acid gas feedconduits 5, 6, and 1 extends through the entrance passageways 36 andprojects a short distance into the furnace, as shown more particularlyin Fig. 5. A sealing collar 4| surrounds each of the waste acidic gasentrance conduits and provides an airtight seal for the closure plate 39through which the acid gas conduit extends. It will be noted byreferring more particularly to Fig. 5 that each of the entrancepassageways 36 are offset to one side of the vertical plane bisectingthe longitudinal center .line of the furnace. An air entrance port 42,as shown more particularly in Figs. 3, 4, and 5, leads tangentially intothe entrance passageway 38-so that the entering air will swirlcircumferentially around the acid gas conduit and within the entrancepassageway 33. Each of the air entrance ports 42 may be provided .with aflange fitting 43 for convenient connection to the branch air entrancelines l1, l3, and I3. respectively.

5 The reaction zones 3, defined by the end walls 25 and the divisionwalls 33, combine the essential functions of mixing chambers,recuperative chambers and reaction chambers. As will be oted byreferring to Figs. 3, 4, and 5, a chim- 10' ney 44 extends verticallydownward from each of the entrance passageways 35. Each of the chimneys44 are built up of heat resistant brick or material and have an internaldiameter approximately the same as the internal diameter of the entrancepassageway 36, and define therein an acid gas and air mixing passageway45 of restricted. cross-section.

The front portion 45 and side portions 41 of each chimney 44 extend downto and rest upon the interior bottom wall section 26 of the furnace,while the rear wall section 48 of the chimney extends downwardly intothe furnace a distance from two-thirds to three-quarters from the topwall section 21 of the furnace. The rear wall section 48 of each chimneyrests upon a horizontal extending wall 43 of flrebrick. The lower sidewall sections 41 of each chimney 44 are extended towards the rear wallsection 28 of the furnace and are joined to the horizontal wall 49 so asto provide a horizontal extending passageway 50 leading from the chimneypassageway 45 towards the rear wall 28 of the furnace. Each of thechimneys 44 is provided with inwardly jutting iirebricks 5i which serveto give the air and acid gas mixture moving down' through the chimneypassageway 45 additional turbulence, thereby to to'insure thoroughmixing and heating thereof.

A reaction chamber compartment wall 52 extends longitudinally througheach reaction compartment and presents a solid wall of flrebrick whichextends from the bottom wall section 25 of the furnace to a planeextending approximately horizontally through the longitudinal centerlineof the furnace. The compartment walls 52 surround but do not close offthe horizontal passageways 50 and extend between the end wall sections25 of the furnace and the division walls 33 thereof. A checker-workbridge wall 53 rests upon the solid compartment wall 52 and extends 56which the air and acid gas mixture is conducted from the horizontalpassageway 50. Each reaction zone or compartment 54 has across-sectional area which is approximately one-third to one-fourth ofthe entire cross-sectional area of 0 the furnace. The bridgework wall53, highly heated by the reaction going on in the furnace, definesescape passageways 55 for the reaction gases which escape through thesehighly heated restricted passageways 55 into the open spaces 55surrounding each chimney 44 where these gases swirl around the chimney44 and preheat the air and acid gas undergoing mixing in the chimneypassage 45. The reaction gases leaving the spaces 55 commingle in theirflow through the passageways 35 and escape through a discharge port 51at the approximate center of the front wall section 29 of the furnace.The discharge port 51 1 may be formed by a steel collar 58 which iswelded or riveted to the steel plates forming the front 11 wall section20 of the furnace, the passageways I! being suitably lined withflrebricl: 82.

At the start of operations. it is necessary to bring the interior of thefurnace and equipment up to approximate reaction temperature. This canbe accomplished by providing a preheating port which extends through therear wall sections 28 of the furnace and leads centrally into each ofthe reaction compartments ll. Suitable burners may be projected intoeach of the ports. Starting burners placed at the ports 00 of thereactor furnace 2 may be operated with any suitable fuel such as naturalgas and for a time sumclent to bring the furnace up to the desiredtemperature of the order of from about 1375 I". to about 1500' F. Whenthe interior of the furnace has been brought up to the desired reactionheat, the burners can be withdrawn and the ports ll sealed 01! by meansof a suitable closure plate 00. At such a furnace temperature immediatereaction of the acid gas-air mixture is insured, and the furnaceoperates continuously without the application of external heat.

In operation. the waste acidic gas enters the respective chimneypassageways 45 of the furnace. through the respective acid gas lines I,0 and I which project through the entrance passageways Sl. in theaccurately metered amounts as hereinbeiore described. Simultaneously airin accurately metered amounts is forced by the blower [5 through airsupply line It and the air inlet-lines l1, l8 and I9. The air enterseach of the entrance passageways in a tangential direction, and thus theair is given a swirling or helical motion as it moves downwardly througheach passageway 16 and into the chimney passageways 40. causing the airstreams to intimately mix with entering waste acidic gas streams as themixtures move down through the chimney passageways 45. The mixed air andwaste acidic gases passing downwardly through chimney passageways arepreheated by direct contact with the highly heated chimney walls. Theproiecting refractory bricks ll further increase the heating eflect, andin addition effect an active turbulence and consequent mixing of thegases. The gas mixture is then deflected at the bottom of the chimneypassageway by the bottom wall section 20 of the furnace through thehorizontal passageway 50, as indicated by the arrows in Figs. 3, 4 and5. The gas stream passes from the horizontal passageway into thereaction chamber 54 and is deflected upwardly by the back wall of thereaction chamber 54. The gas stream continues to travel through thehighly heated restricted passages 55 in the checker-work wall 53, thenceinto the passages 58 which surround the chimney 44. The reaction gasesin the passages 50 heat the walls of the chimneys I4 and therebyindirectly heat the stream of air and acid gas mixture, movingdownwardlythrough the passage 45 in the chimney 44. The reaction gasesleave the spaces 50 surrounding each of the chimneys,

and converge through passageway 35 and commingle in their discharge flowthrough the discharge port 51.

In the reaction zone the reaction conditions are adjusted so as toestablish a temperature in the eiiluent reaction gases leaving port 51of not substantially less than l600 F. and preferably between about 1800F. and 2400 F. with the practical optimum range of from 1850 F. to 2000"F., by deflecting entering waste acidic gas to No. 1 converter. As willbe appreciated, this exit temperature will be influenced by the degreeof ini2 sulation of the furnace, the hydrocarbon content and thehydrogen sulphide content of the entering waste acidic gas.

The furnace may be provided with conveniently arranged clean-out ports0| which are normally sealed off by suitable closure plates 02. Thefurnace may be strengthened and stiilened by a suitable stifleningframework 03.

As shown in Figs. 1 and 2, the reaction gases pass from the outlet port01 of the furnace 2 through conduit 00 and thence to the waste heatboiler 00. The waste, heat boiler may be'of any desired and efficienttype and of suitable capacity to reduce the temperature of the reactiongases down to the order of from approximately 450 F. to about 800 F.with an approximate optimum temperature of around 600 F. As shown inFigs. 1 and 6, the boiler 00 is provided with one or more partitions 01therein providing a circuitous passageway for the reaction gases whichare discharged from the bottom of the boiler into the outlet conduit 60.The boiler is provided with water tubes 69 and a steam drum 10. Feedwater from supply line H is fedto the economizer 12 and passes throughserpentine tubes therein and is discharged therefrom at a raisedtemperature into line 13 and into the steam drum 10. An automatic feedwater regulating valve 14 is provided in water inlet line II which iscontrolled by the water level in the steam drum 10. Steam is dischargedfrom the drum through the high pressure line I5. Flow of steam isrecorded by the meter 16. A supply of steam may be tapped oil throughtap line 11 to furnish any steam required for subsequent processoperations. Tap line 'l'i'may have therein a suitable steam flow controlvalve ll.

The reaction gases passing through the waste heat boiler 50 aredischarged through the conduit 00 to preheater or heat exchanger andthrough the conduit 0! to the converter 02. In the preheater 00 thereaction gases pass in indirect heat exchange relationship to gaseswithdrawn from the upper portion of condensing tower 83.-

In passage through the preheater 00 the reaction gases entering fromline 60 at a temperature 450 to 800 F. are reduced in temperature tobetween about 350 F to 750 F. with an optimum temperature ofapproximately 500 F.

The reaction gases entering the top of converter 02 flow downwardlythrough a bed 0 of a suitable catalyst such as alumina, bauxite, ironoxide, calcium sulphate, silica gel or other catalysts which facilitatethe formation of elemental sulphur and is sufliciently refractory towithstand the operating temperatures. The catalyst is preferablyemployed in the form of a granular mass supported on a heat andcorrosion resistant foraminous member such as a stainless steel screen81.

In event that air in excess of a stoichiometric amount is admitted intothe furnace 2, the reaction gases entering the converter 82 through line8! may be mixed with predetermined amounts of acid source gas divertedthrough line i0 as shown in Fig. 1 so that a stoichiometrical balance isattained in the converter. In this manner a proportion of acid sourcegas may be treated in the converter 02 without passing through the hightemperature reaction zones in furnace 2, in which case the temperatureof the discharged reaction. gas'is about 300 F. above the temperature ofthe entering reaction gas, which temperature should be less than 1000 F.

70 The depth of the catalyst may vary considerlyst by the rapidlyflowing gas stream.

ably depending upon such factors as the activit1 of the catalystsemployed, the particle size of the granules and the like. The quantityemployed, as will be understood. is chosen to insure maximum conversionwithout undue building up of a 5 too great resistance to gas flow. Thearea of the catalytic bed similarly may be varied and is essentiallydetermined by the quantity of sulphur to be produced in the unit. It-hasbeen found.

desirable in practice to cover the catalyst bed The reaction takingplace in the converter is exothermic. In the typical operation thetemperature of the gas discharged is about one hundred degrees higherthan the inlet temperature; the inlet temperature ranging from 350 to700 F. with an optimum of approximately 500 F. and at the outlet 88 at atemperature of from 450 to 800 F. with an optimum average of about 600F. The treated gases are discharged from the;

converter through the side ducts 88 and pass 5 through a common conduit89 to the economizer The gases passing downwardly through the economizerI2 preheat the boiler feed water up;

to a temperature of the order of from-800to 450 F. in the mannerdescribed, and as aresult of this abstraction of heat, the gases arereduced in temperature to approximately 370 F. to'450 F., with anoptimum average of about 400 F; The gases pass from the bottom of theeconomizer '35.

12 through conduit 90 to a lower portion of the condensing tower 83. Ashas been previously pointed out, the condensing tower 83 functions tocondense and liquefy the sulphur vapor content of the gas and 40 toaccumulate it as a liquid phase product. The tower may be of anysuitable construction. is shown, it is provided in the base with a tankSI for containing molten sulphur. Such molten sulphur may be maintainedat a desired prede- 1:;

gases supplied by line 68. As a result of such heat termined temperatureby means of the coil .92 which may be fed with cooling water enteringvalve controlled line 93. When the unit is operating, water may beforced through the coil 92 to abstract heat from the molten sulphur atthe de-" 'su sired refluxing temperature. In typical operation waterenters the coil at about 80 F. and is discharged through line 92' atabout 120 F. The coil may .be connected with-the steam line 84 throughwhich steam from steam line 11 may' at be admitted during a shut-downperiod or at any other time when it is desirable to heat the sulphurcontained in the tank 8|.

The cooled molten sulphur from the tank 9| at the base of the tower, asshown, is forced by on pump 95 driven by motor 95' through line 96 tothe spray heads or similar distributing means 91 positioned in the upperpart of the tower. The molten sulphur flows downwardly intimatelycontacts and cools the countercurrently flowing es molten sulphur intodroplets or films which cascade down the tower sequentially from bame tobaiile, thus insuring maximum contact with upflowing gases andconsequent effective heat exchange. The molten sulphur accumulating indrained oil or intermittently through the overflow weir line 88 and theinsulated line 88' to the receiving vessel III, which may be suitablyheated to allow ready removal of the elemental sulphur in liquidlform.The line Il may be provided with an extension 68" for the purpose oftappin and draining the tank II when desired.

In order to secure maximum liquefaction of the sulphur vapors enteringthe tower 88, it is desirable that the overhead reaction gasesdischarged from the tower through line 84 be held at approximately 260F., that is to say, the overhead reaction gas escaping from the towershould be as close to the freezing point of sulphur as possible, andpreferably only suillciently above the freezing point to prevent thesolidification of sulphur in the upper part of the tower.

In the tower, due to the direct contact of the molten sulphur with theentering reaction as. the temperature of such entering reaction gas israpidly reduced. For example, in typical operation the entering reactiongas is discharged fromthe eoncomizer 12 to the condensing tower 88 at atemperature of about 400 F. In passing upwardly through the tower, thereaction gases are substantially cooled and are discharged at atemperature of about 260 F. It is found that when operating the processin the manner described, the entering reaction gasesdischarged from thetop of the tower 88 are substantiallydenuded of free sulphur andrcontain but a small amount of combined sulphur.

Numerous tests indicate that the combined sulphur (H:S+SO2) in suchgases is only approxi mately 2% to 5%. If desired, this gas may bedischarged from the system. Additional quantities of sulphur, however,can be recovered economically from such overhead reaction gas in themanner shown in Figs. 1 and 2.

As previously explained, the overhead reaction gases from the condensingtower 83 flow into the preheater at a temperature of approximately 260F. and there pass in indirect heat exchange relationship with highertemperature reaction exchange the temperature of the overhead reactiongas from tower 83 is raised to approximately 400 F. to 700 F. with anoptimum temperature of about 450 F. This overhead reaction gas is passedto the second catalytic converter 86 which sulphur compounds theconverter 86 can be appreciably smaller than converter 82. The catalystbed 0 in the converter 86 should be suflicient oversize area to takecare of unexpected loadsand avoid any appreciable back pressure. Inpassage through converter 86 a substantial proportion of these sulphurcompounds are reduced to elemental sulphur in vapor form. In typicaloperations the content of the hydrogen sulphide and sulphur dioxide inthe gas discharged from this second converter is approximately one percent by volume.

The gases are discharged from converter 86, at v a temperature of fromabout 420 F. to 600 F.,

are passed through conduit IN to the lower section of a secondcondensing tower I02, which is similar in structure and function totower 83.

A water cooler I03 is preferably connected to-gas outlet conduit l0! soas to cool the gases therein to approximately 300 F. Cool water issupplied the tank ill at the base of the tower may be .75 to thereaction gas cooler I08 through water 15 line Ill and the hot water fromthe cooler may be piped from outlet line I" to the steam drum 10.

The tower II! is provided with the tank I" at the bottom thereof for theaccumulation of molten sulphur, the temperature of which is controlledby the coil Il'l. Water may be passed through the coil ill from lineIII! to abstract heat from the molten sulphur in the manner previouslydescribed. The coil may also be connected with steam line I6! suppliedby tap line Il so that an elevated temperature may be establishedin thetank at any time, as for example during shut-down periods and the like.Molten sulphur is pumped to the top of the tower through line III bypump Ill operated by motor The molten sulphur is distributed by means ofa distributor over the baflle plates 98 in the tower III and isrecurrently dispersed into droplets or filaments which intimatelycontact the upwardly flowing reaction gases and cool these gases to theliquefaction point of sulphur, which liquefied sulphur accumulates inthe tank II. The accumulated sulphur in tank I is continuously orintermittently withdrawn through weir line H! and is dischargedintoinsulated line 8!" and into the storage vessel I". The temperaturerecorders Ill record the temperature of the molten sulphur circulatedthrough lines SI and III. The

gases and vapors uncondensed in the towers I02 pass out the stack I I4.This eilluent gas contains substantially all the carbon dioxide in theacid entering waste gas feed, the nitrogen from the air feed and watervapor contained in the waste acid gas and air feed, and produced duringthe reaction, together with the indicated ,minor amounts of hydrogensulphide and sulphur dioxide which is so small that it may be dischargedinto the atmosphere. Pyrometer points and pressure gages II! may belocated at various important points in the system so that full controlover the operation may be obtained.

A plant of the type described operates efficiently on waste acidic gashaving a hydrogen sulphide content of the order of 60 per cent or moredown to about per cent and containing in addition carbon dioxide, watervapor and sundry hydrocarbons. In most instances it has been found thatfor the economic commercial recovery of sulphur the waste acidic gasshould not be below about 15 per cent to per cent of hydrogen sulphide,unless in large quantities. Obviously, however, where the criteria ofpublic health and the nuisance character of the source material becomeimportant in a particular case, the novel operation may be desirable ongases containing relatively low concentrations of hydrogen sulphide, thecost being considerably reduced by the credit derived from the recoversulphur.

As noted hereinbefore, the unit presents a wide permissive flexibilityin operation. In lieu of the described operation, 1. e., in which all ofthe waste acidic gas and air are passed through the furnace, operationsmay be conducted in which a split feed of entering waste acidic gas isutilized. In this operation, as previously described, all of 16 ficientto maintain continuous conversion of the split gas feed.

As will have been noted, the striking emciency of the operation is dueto a considerable degree to the design of, and effective control ofoperating conditions in the furnace. It will be further noted that theprocess depicted in Fig. l represents what'might be called the optimumoperation in that it is designed to recover the maximum amount ofsulphur from the gaseous source material. There are a number ofoperations of more simplified form and which require somewhat lessapparatus which may be conducted, a typical example of which is shown inFig. 6. Whereas. the process disclosed in Fig. 1 involves in eflect,three progressive conversion stages, 1. e., conversion in the furnaceand sequential conversions in converter 82 and converter 86, the methodshown in Fig. 6 utilizes two conversion stages, namely the hightemperature furnace conversion and one lower temperature catalyticconversion stage with appropriate intermediate cooling and temperaturecontrol. The principles of operation of the unit shown in Fig. 6 are thesame as those embodied in Fig. 1, the only essential difference beingthat in such operation the ultimate percentage recovery of sulphur isless than the potential recovery which is achieved in the unit of Fig.1.

As shown in Fig. 6 the essential units of the apparatus include thefurnace 2, the waste heat boiler 66, the heat exchanger 80, theeconomizer 12, the first scrubbing tower 83, catalytic converter 86, thewater cooler I03, and the second scrubbing tower I02. The structure andfunction of these elements are as previously described for Fig. 1.

In operation, entering waste acidic gas and stoichiometricallyproportioned amounts of air are concurrently fed to the furnace throughthe lines I and I6, vrespectively. In the furnace, which is similar instructure as that shown in Figs. 3, 4 and 5, the gases are homogeneouslymixed, highly heated and are reacted to produce a proportion ofelemental sulphur in vapor form. The reaction gases pass from thefurnace, at a temperature of from approximately 1600 F. to 2400" F.,through the conduit to the waste heat boiler 66. The boiler is providedwith the steam drum 10 to which feed water is admitted from line 13 andfrom which generated steam is withdrawn 7 through line IS.

The feed water, if desired, may be preheated in the economizer I2supplied with water through line H and discharged into branch line I3which feeds into the feed water line 13. Additional hot waterisgenerated by the cooler I03 supplied with water through line I anddischarging into hot water line I05 which may also supply the feed waterline I3.

The reaction gases are discharged rom the boiler 68 into the conduit itat a temperature ranging from 450 to 800 F. and are conducted into theheat exchanger where they are cooled down and discharged at atemperature of 400 to 500 F. through conduit I20 leading into the upperend of the economizer'l2.- In the heat exchanger the air required forthe operation is passed through the furnace admixed with from i; to ormore of the entering waste acidic gas and the remaining waste acidic gasis fed to the converter 82 through line It in a manner to obtain astoichiometric balance in the converter 83. The exothermic heatdeveloped in the converter is suf- II the reaction gases from the boilerpreheat the overhead reaction gases which are discharged from the top oftower 83 through the line 84. The reaction gases entering the economizerare cooled by the water entering the lower end of the economizer anddischarge into conduit at a temperature of about 300 F. at whichtemperature the reaction gases enter the lower end of II the scrubbingtower 83.

As has been previously described, the tower 03 is provided with a tank9i located in the base for the accumulation of molten sulphur. Thesulphur in tank 9| may be maintained at the described desirabletemperature of between 260 F. and about 280 F. by means of the coil 02through which a cooling medium is admitted from line 93 or a heatingmedium is admitted through line 94, either of which is dischargedthrough line 92.

Reaction gases flowing upwardly through the tower 83 are contacted bystreamlets of molten sulphur forced to the upper section of the towerthrough line 96 by pump 95 driven by motor As a result of such contact,as has been explained, the gases are cooled and the sulphur vapors arecondensed and collected in the tank 9|. The molten sulphur is withdrawnthrough weir line 99 into the accumulator tank I00. The temperature ofthe sulphur in tank I00 may be maintained at the desired temperature bya, heating coil.

The overhead reaction gases from the tower 83 enter the heat exchanger80 at a temperature of from about 260 F. to 280 F. and in passagethrough the heat exchanger 80 are preheated to the order of from about400 F. to about 500 F. and are then passed to the converter 86 whereinfurther conversion of sulphur-containing gases to free sulphur in vaporphase occurs. The converter 06 is of the same construction as abovedescribed, and is provided with a bed of catalytic material 0 of theclass previously mentioned.

- Reaction gases pass from the converter 86 at atemperature of 420 to550 F. and thence to the tower I02 through conduit IOI. These reactiongases are preferably cooled by the cooler I03 in conduit IN to atemperature of about 300 F.

The reaction gases are then contacted with molten sulphur in tower I02pumped from the tower tank I06 by pump H0 driven by motor 0' throughline I to the top of the second tower I02. Themolten sulphur descends inthe tower I02 in the form of droplets sequentially from baflie to baflle98 and functions to condense the sulphur vapor contained in the gas andaccumulate it in the tank I06 at the base of the tower. Such moltensulphur may be drawn from the base of the tower through the weir lineII2 to the accumulator tank I00. The desired temperature of from 260 F.to about 280 F. is maintained in the sulphur tank I06 by means of thecooling coil I01. As heretofore described, this coil may be connected toa water line I08 and to the steam line I09, for cooling or heating thesulphur as desired.

It will be noted that all units of the apparatus are so designed thatany molten sulphur which may form at any point in the system will drainthrough the system or through appropriately located drain lines leadingto the molten sulphur tanks so that the formation of molten sulphur inthe system does not impede or interfere with the operation.

It will now be seen that the process comprises a series of steps whichare intimately correlated to insure novel results. Exceptionally highyields of elemental sulphur from hydrogen sulphide are attained byutilizing the novel recuperative furnace where intimate mixing, rapidpreheating and high reaction are attained at the optimum hightemperatures. The sensible heat in the exit gases are not onlyultimately recovered, as for example, in a form of available steam, butalso such heat is utilized currently in the cycle to 18 adjust thetemperature of the gases discharged from the scrubber tower 02 to thatrange which insures optimum conversion in the catalytic reduction stage.

It will also be appreciated that technical utilization may be made ofthe tail gases. As noted,

these have a high content of carbon dioxide. Whenever desired, suchgases may be further treated to purify them and to recover the carbondioxide in substantially pure state as a gas, liquid or solid.

Attention is directed to our copending applications Serial No. 574,608,filed January 25. 1945; Serial No. 574,607, filed January 25, 1945, andSerial No. 83,906, filed March 28, 1949.

While preferred embodiments of the invention have been described, it isunderstood that these are given didactically to illustrate thefundamental principles involved, and not as limiting the useful scope ofthe invention to the particular embodiments illustrated.

What is claimed is:

1. A method of producing elemental sulphur from sulphide-containinggases by reaction with a quantity of air regulated to eflect theformation of elemental sulphur which comprises, passing a potentiallyreactive gas mixture through a confined reaction zone, effectingoxidizing reactions of said mixture in said zone, discharging thegaseous products of reaction from said zone at a temperature of betweenabout 1800" F. to about 2400 F., cooling the exit reaction gases,contacting said cooled reaction gases with a catalyst, scrubbing saidcatalyst treated gases with a coolant to condense and recover elementalsulphur' therefrom, passing the scrubbed gases in indirect heat exchangerelationship with gases discharged from said reaction zone to preheatsaid scrubbed gases to a temperature of between about 350 F. and '100F'., contacting such preheated scrubbed gases with a catalyst to effectfurther reaction of sulphur-containing gases therein to elementalsulphur, and separating and recovering elemental sulphur thus formed byscrubbing such gases with a coolant.

2. A method of producing elemental sulphur from sulphide-containinggases by reaction with a quantity of air regulated to efiect theformation of elemental sulphur which comprises, passing streams of gasand air to a confined reaction zone, effecting reaction of the mixturein said zone, withdrawing gaseous products of reaction fromsaid zone ata temperature of about 1600 F. to about 2400 F., cooling the exitreaction gases, scrubbing such cooled reaction gases with a coolant tocondense and recover elemental sulphur therefrom, passing the scrubbedreaction gases in indirect heat exchange relationship with gasesdischarged from the reaction zone to raise the temperature of thescrubbed gases to between about 400 F. to about 600 F., contacting suchpreheated gases with a catalyst to efl'ect further reaction of thesulphur-containing gases to elemental sulphur, cooling the reacted gasesto a temperature of between about 270 F. and 500 F. and scrubbing suchcooled gases with a coolant to condense and recover elemental sulphurtherefrom.

3. A method of producing elemental sulphur from sulphide-containinggases by reaction with a quantity of air regulated to efl'ect theformation of elemental sulphur which comprises, passing streams of thegas and air to a confined reaction zone, eifecting reaction of themixture in said zone. withdrawing gaseous products of reaction from thesaid zone at a temperature of between about 1600 F. to about 2400 F.,reducing the temperature of such reaction gases to from about 350 toabout 700 F., contacting the cooled reaction gases with a catalyst toeffect further conversion of sulphur-containing compounds to elementalsulphur, cooling the products of reaction to a temperature of from about270 F. to about 470 F., condensing and recovering sulphur therefrom byscrubbing the reaction gases with liquid coolant, raising thetemperature of the scrubbed gases to between about 400 F. to about 600F., contacting such'preheated scrubbed gases with a catalyst to effectfurther reaction of the sulphur containing gases thereof to elementalsulfur, and separating and recovering the elemental sulfur thus formed.

4. A method of producing elemental sulphur from sulphide-containinggases by reaction with a quantity of air regulated to effect theformation of elemental sulphur which comprises, passing a mixture of thegas and air through a confined reaction zone, eifecting reaction of themixture in said zone, discharging the reaction gases from the zone at atemperature of the order of from about 1600 F. to about 2400 F., passingsuch reaction gases to a waste heat boiler to abstract a predeterminedquantity of heat therefrom, passing such preliminarily cooled gasesthrough a heat exchanger to reduce the temperature -of the reactiongases to the order of from 350 F. to 700 F., contacting such cooledreaction gases with a catalyst to effect further reaction of thesulphur-containing gases to elemental sulphur, reducing the temperatureof such reaction gases to between about 270 F. and 400 F., scrubbingsuch reaction gases with a coolant to condense and recover elementalsulphur therefrom, passing the scrubbed gases through the said heatexchanger to thereby preheat the scrubbed gases to a temperature ofbetween about 350 F. to 600 F., contacting such scrubbed gases with acatalyst to effect conversion of the sulphur-containing compoundstherein to elemental sulphur, and scrubbing said reaction gases with acoolant to recover sulphur therefrom.

5. A method of producing elemental sulphur from hydrogensulphide-containing gases by reaction with a quantity of air regulatedto effect the formation of elemental sulphur which comprises, passingstreams of the gas and air to a confined reaction zone, effectingreaction of the mixture in said zone, withdrawing gaseous products ofreaction from the said zone, cooling said reaction gases to apredetermined temperature of from about 350 F. to about 700 F.,contacting the cooled reactiongases with a catalyst to effect furtherinter-reaction of the sulphurcontaining gases to elemental sulphur,cooling the reaction gases so treated, scrubbing the cooled reactiongases to remove the elemental sulphurtherefrom, preheating the scrubbedgases to a temperature of between about 350 F. and 700 F., contactingsuch preheated gases with a catalyst which is effective to convertsulphurcontaining compounds to elemental sulphur, and removing andrecovering elemental sulphur therefrom.

6. A method of producing elemental sulphur from sulphide-containinggases which includes. feeding the sulphide-containing gases and airunder pressure into a restricted passageway hav ing heat transfersurfaces, passing the gas and air mixture through said restrictedpassageway into a confined reaction zone, directing the gaseous productsof reaction discharged from said passageway into heat exchange with theexterior surfaces of said passageway to thereby heat the gaseousmaterials travelling through said passageway by indirect heat exchange,discharging said gaseous materials from said confined reaction zone at atemperature from about 1600 F. to about 2400 Ft, cooling the dischargedgases to an adjusted temperature of between about 400 F. to 700 F.,passing the cooled reaction gases through a bed of catalyst, cooling thereaction products discharged from said catalyst bed, scrubbing thecooled reaction gases with a coolant to recover elemental sulphurtherefrom, passing the discharged gases into contact with a catalyst toeflect inter-reaction of the remaining sulphur content of said gases toelemental sulfur, and separating and recovering the elemental sulfurtherefrom.

7. In a processing system for treating sulphidecontaining gases torecover-elemental sulphur therefrom which system incorporates a heatingzone leading to a catalyst zone, the process which includes, feeding thesulphide-containing gases to said system prior to entry of said gases tosaid catalyst zone and wherein at least a substantial part of said gasesare fed to said heating zone, feeding a substantially stoichiometricquantity of air to said heating zone regulated in amount to effect theformation of elemental sulphur from the sulphide-containing gass fed tothe system, effecting reaction in said heating zone of the gas and airsupplied thereto, withdrawing the gaseous products of reaction from saidheating zone at a temperature of about 1600 F. to about 2400 R, coolingthe reaction gases supplied to said catalyst zone to an adjustedtemperature of from 400 F. to 700 R, passing the cooled reaction gasesinto contact with a catalyst in said catalyst zone to effect furtherinter-reaction of the sulphur-containing gases to elemental sulphur,scrubbing the catalyst treated reaction gases with a coolant to recoverthe elemental sulphur content of said treated gases, passing thedischarged" gases into contact with a catalyst to effect inter-reactionof the remaining sulphur content of said gases to elemental sulphur, andseparating and recovering the elemental sulphur therefrom.

8. In a processing system for treating sulphidecontaining gases torecover elemental sulphur therefrom which system incorporates a heatingzone leading to a catalyst zone, the process which includes, feeding thesulphide-containing gases to said system prior to entry of said gases tosaid catalyst zone and wherein at least a substantial part of said gasesare fed to said heating zone, feeding a substantially stoichiometricquantity of air to said heating zone regulated in amount to effect theformation of elemental sulphur from the sulphide-containing gases fed tothe system, effecting reaction in said heating zone of the gas and airsupplied thereto, withdrawing the gaseous products of reaction from saidheating zone at a temperature of about 1600' F. to about 2400 F..cooling the reaction gases, passing the cooled reaction gases intocontact with a catalyst in said catalyst zone to effect furtherinter-reaction of the sulphur-containing gasesto elemental suiphur,separating and recovering the elemental sulphur content of said catalysttreated gases, passing the discharged gases into contact with a catalystto effect inter-reaction of the remaining sulphur oontentof said gasesto elemental sul- 21 phur, and separating and recovering theelementalsulphur therefrom.

9. In a processing system for treating sulphidecontaining gases torecover elemental sulphur therefrom which system incorporates a heatingzone leading to a catalyst zone, the process which includes, feeding thesulphide-containing gases to said system prior to entry of said gases tosaid catalyst zone and wherein at least a substantial part of said gasesare fed to said hea zone, feeding a substantially stoichiometricquantity of air to said heating zone regulated in amount to efiect theformation of elemental sulphur from the sulphide-conta ng gases fed tothe system. effecting reaction in said heating zone of the gas and airsupplied thereto, withdrawing the gaseous products of reaction from saidheating zone at a temperature of about l600 F. to about 2400 R, coolingthe reaction gases supplied to said catalyst zone to an adjustedtemperature of from 400 F. to 700 F., passing the cooled reaction gasesinto contact with a catalyst in said catalyst zone to eflfect furtherinter-reaction of the sulphur-containing gases to elemental sulphur,scrubbing the catalyst treated reaction gases with a coolant to recoverthe elemental sulphur content therefrom, heating the scrubbed gases to atemperature of from 300 F. to 700 F.,contacting the scrubbed and heatedgases with a catalyst to eifect inter-reaction of the remaining sulphurcontent of said scrubbed gases to elemental sulphur, and separating andrecovering the elemental sulphur therefrom. I

10. A method of producing elemental sulphur from sulphide-containinggases by reaction with a quantity of air regulated to effect formationof elemental sulphur which comprises passing a reactive gas mixturethrough a confined reaction zone, effecting reaction of the mixture insaid zone, withdrawing gaseous products of reaction from said Zone at atemperature of between approximately 1600 F. and 2400 F., cooling theexit reaction gases by indirect heat exchange with the initial reactivegas mixture, scrubbing such cooled reaction gases with a coolant tocondense and recover elemental sulphur therefrom, passing the scrubbedreaction gases in indirect heat exchange relationship with gasesdischarged from the reaction zone to raise the temperature of thescrubbed gases to a temperature of between approximately 400 F. and 600F., contacting such preheated gases with a catalyst to effect furtherreaction of the sulphur-containing gases to elemental sulphur, coolingthe reaction gases to a temperature of between approximately 270 F. and500 and scrubbing such cooled gases with a coolant further to condenseand recover elemental sulphur therefrom.

11. A method of producing elemental sulphur from sulphide-containinggases by reaction with .a quantity of air regulated to effect theformation of elemental sulphur which comprises passing a reactive gasmixture through a'confined reaction/zone, effecting reaction of themixture in said zone, withdrawing gaseous products of reaction from saidzone at a temperature of beof between approximately 270 F. and 500I'.',and scrubbing such cooled gases with a coolant further to condense andrecover elemental sulphur content therefrom. a 12. A method of producingelemental sulphur from hydrogen sulphide-containing gases by reactionwith a quantity of air regulated to effect the formation of elementalsulphur which comprises passing a mixture of gas and air to a confinedreaction zone, eflecting reaction of the mixture in said zone,withdrawing gaseous products of reaction from said zone, passing thegaseous products of reaction in indirect heat exchange relationship withthe initial mixture of gas and air, cooling the gaseous reactionproducts to a predetermined temperature of between approximately 350 F.and 700 F., contacting the cooled reaction gases with a catalyst toeflect further inter-reaction of the sulphur-containing gases toelemental sulphur, cooling the reaction Eases so treated, scrubbing thecooled reaction gases to remove the elemental sulphur therefrom,preheating the scrubbed gases to a temperature of between approximately350 F. and 700 F., contactlng such preheated gases with a catalyst whichis effective to convert sulphur-containing compounds to elementalsulphur, and removing and recovering elemental sulphur therefrom.

13. A'method of producing elemental sulphur from hydrogensulphide-containing gases by reaction with a quantity of air regulatedto effect the formation of elemental sulphur which comprises passing amixture of gas and air to a confined reaction zone, eiiecting reactionof the mixture in said zone, withdrawing gaseous products of reactionfrom said zone, cooling said gaseous reaction products to apredetermined temperature of between approximately 350 F. and 700 F.,contacting the cooledreaction gases with a catalyst to effect furtherinter-reaction of the sulphur-containing gases to elemental sulphur,cooling the reaction gases so treated, scrubbing the cooled reactiongases to remove elemental sulphur therefrom, preheating the scrubbedgases to a, temperature between approximately 350 F. and 700 F. bypassing said gases in indirect heat exchange relationship with gasesdischarged i'rom the reaction zone, contacting such preheated gases witha catalyst to effect further reaction of the sulphur-containing gases toelemental sulphur, cooling the reaction gases to a temperature ofbetween approximately 270 F. and 500 F., and scrubbing such cooled gaseswith a coolant to condense and recover elemental sulphur therefrom.

14. A method of producing elemental sulphur from hydrogensulphide-containing gases by reaction with a quantity of air regulatedto effect the formation of elemental sulphur which comprises passing areactive gas mixture through a. confined reaction zone, effectingreaction of the mixture in said zone, withdrawing gaseous products ofreaction from said zone, mixing said gaseous reaction products with afurther quantity of sulphide-containing, gases, cooling the mixed gases,contacting th'e cooled reaction gases with acatalyst to effect furtherinter-reaction of the sulphide-containing gases to form elementalsulphur, cooling the reaction gases so treated, scrubbing such cooledreaction gases to condense and recover elemental sulphur therefrom,preheating the scrubbed gases to a temperature of between approximately350 F. and 700 F.', contacting such-preheated gases with a catalyst toeffect further reaction of the sulphur-containing gases 23 toelemental-sulphur, and removing and recoverin: elemental sulphur contenttherefrom.

15. A method-of producing elemental sulphur irom-sulphide-containinggases by reaction with a quantity of air regulated to effect theformation of elemental sulphur which comprises passing a mixture ofass-and air through a confined reaction none, discharging the gaseousproducts of reaction iron the acne at a temperature of betweenapproximately 1850' F. and 2000 F., passing the nit saloons reactionproducts in indirect heat exchange relationship with the initial mixture(If-Ill and air, passing such cooled gaseous reacto a waste heat boilerto abstract a quantity of heat therefrom, the cooled gaseous reactionproducts was heat exchanger to reduce the temperathe laseo'us reactionproducts to a tempasture of between approximately 350 F. and

w ll; mixing such cooled reaction products 'with-s quantity ofsulphide-containing as, mixed gases with a catalyst to elicit furtherreaction of the sulphide-contsinina gases to form elemental sulphur,passing theueooled aaseousreaction product through a M economiser unitto reduce the tempeatu're of such gaseous reaction products to atemperatm'e' of between approximately 270' R, and W1, utilizing theheated water therefrom" A a iced !or laid waste heat boiler, scrubbingthe cooled gaseous reaction products from said 11th a coolant tocondense and resulphur content therefrom, passint-the scrubbed sasesthrough said heat ex- 24 changer to thereby preheat the scrubbed casesto a temperature of between approximately 350' 1". and 600 F.,contacting such scrubbed gases with a catalyst to effect furtherconversion of the suiphur-containing compounds therein to elementalsulphur, and scrubbing said gases with a coolant to recover elementalsulphur therefrom.

REFERENCES CITED The following references are of record in tbe file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,922,872 Thompson Aug. 15. 19382,021,372 Mast Nov. 19. 1985 2,090,217 Merriam Aug. 17, 1937 2,092,386Baehr Sept. 7, 1037 2,092,794 Bacon et a]. Sept. 14,1937 2,200,529 BaehrMay 14, 1940 2,386,202 Fernelius etal. Oct. 9, 1945 2,403,451 Nevins etal. July 9. 1946 FOREIGN PATENTS .Number Country Date 185,780 GreatBritain Sept. 7, 1922 419,787 Great Britain Nov. 19, 1934' OTHERREFERENCES Ser. Nos. 362,376 and 398,346, Koppel-s (A.

P. C.), published April 27, 1943.

1. A METHOD OF PRODUCING ELEMENTAL SULPHUR FROM SULPHIDE-CONTAININGGASES BY REACTION WITH A QUANTITY OF AIR REGULATED TO EFFECT THEFORMATION OF ELEMENTAL SULPHUR WHICH COMPRISES, PASSING A POTENTIALLYREACTIVE GAS MIXTURE THROUGH A CONFINED REACTION ZONE, EFFECTINGOXIDIZING REACTIONS OF SAID MIXTURE IN SAID ZONE, DISCHARGING THEGASEOUS PRODUCTS OF REACTION FROM SAID ZONE AT A TEMPERATURE OF BETWEENABOUT 1800*F. TO ABOUT 2400*F., COOLING THE EXIT REACTION GASES,CONTACTING SAID COOLED REACTION GASES WITH A CATALYST, SCRUBBING SAIDCATALYST TREATED GASES WITH A COOLANT TO CONDENSE AND RECOVER ELEMENTALSULPHUR THEREFROM, PASSING THE SCRUBBED GASES IN INDIRECT HEAT EXCHANGERELATIONSHIP WITH GASES DISCHARGED FROM SAID REACTION ZONE TO PREHEATSAID SCRUBBED GASES TO A TEMPERATURE OF BETWEEN ABOUT 350*F. AND 700*F.,CONTACTING SUCH PREHEATED SCRUBBED GASES WITH A CATALYST TO EFFECTFURTHER REACTION OF SULPHUR-CONTAINING GASES THEREIN TO ELEMENTALSULPHUR, AND SEPARATING AND RECOVERING ELEMENTAL SULPHUR THUS FORMED BYSCRUBBING SUCH GASES WITH A COOLANT.